Improved process of preparing wood-fibre for paper stock



mihed gime @sind @Mina GEORGE E, MARSHALL, OF LAUREL, INDIANA.

Letters Patent No. 94,228, :lated August 31, 1869.

Mew-

.The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may conce/m Be it known that I, GEORGE E. MARSHALL, of Laurel, in the county of Franklin, and State of Indiaua, have invented certain -new and useful Improvements in the Process of Preparing Wood-Pulp for -Paper; and I d0 hereby declare that Ythe following is My invention relates to the preparation of paperv stock from wood; and

It consists in a novel manner of 'treating the wood with steam and water, as hereinafter explained.

The accompanying drawing represents a side elevation ofthe apparatus used in applying my process.'

This apparatus dii'ers but little from that ordinarily used in the prepa-ration 'of paper stock, the diier ence consistingisimplyinthe arrangement of the pipes.l In preparing stock, I irst put the wood, suitably prepared, into an ordinary close boiler, and turn on steam from a boiler, through pipe c.

. In this manner I subject the wood to a steam-pressure of about eighty pounds, more or less, for about two hours, the boiler being kept closed, so as to'conne the steam therein during this operation.

I then open'a cock inpipe e, which connects the bottom of the boiler A with a tank, B, containing water, and located above oron a level with the top of the boiler, as represented in the drawing.

The steam in the boiler A is then blown from the boiler into the tank B, thereby heating the water'in At this stage of the process, the wood will be found tovbe considerably softened and spongy, and-having av strong acid taste, while the pores of the wood are opened. a

. I now fill the boiler within'about six inches of the top with the heated water from the tank B, which flows in through the pipe e, then close the boiler, and tur'n on the steam again from the boiler, running the pressure up to about seventy pounds, after which I blow the steam and water both off through pipe d, at the bottom of the boiler.

If the wood be examined at this stage of the process, it will be found to be nearly or quite free from acid, the steam having rst opened the pores and penetrated the wood thoroughly, dissolving the gums, and setting free the acids, both of which are then absorbed, or taken up by the water, and carried oii' with it, when. the'latter is blown off, as described.

Or, instead of injecting heated water from the tank, a' jet of cold water may be injected at the top of the boiler, thereby condensing what steam there may be 4mass treated therewith in the usual manner.

Now, by'this preliminary steaming and rinsing of the wood, I ind that a solution of 4 Baum is amplysufficient to complete the process, andproduce fibre,

remaining in the boiler, this condensation creating a partial vacuum inthe boiler, and thereby causing thev wood to expand, and, ofcourse, opening still more its ores.

p The boiler should be nearly iilled with water, which may be either 'warm water from the tank B, or cold water, injected as before; and, when thus filled with water, I apply steam to the boiler, using super-heated steam, so as quickly to run the pressure up to about seventy pounds, and heat the mass.

I then blow off-the water by letting in steam,'and, as the waterhas to' pass down through the mass of wood to escape at the bottom, it absorbs and carries off with it nearly all the gums and-acid contained in the wood.

After blowing ofi' the water, it is desirable to let fresh steam pass through the boiler A, and escape through pipe d or f for a short time, this passage of the steam through the mass tending to expelv therefrom all water, with its "gum and acid held in solution.

. When this is done. the pipes are closed,v and an alkaline solution is injected into the' boiler', and the in all respects equal to that-produced by the ordinary process, witlna solution of 9;. .and, by repeating the process of steaming and rinsing the wood before applyin'g the alkaline solution, a still weaker solution may be made to answer.

Thusfby my improved process, I find, by actual experiment, that I can save from one-half to twothirds of the cost of the chemicals Vordinarily used; and, as the entire process is conducted without removing the wood from the boiler, or handling it in any way, it renders the process extremely simple 'and I am aware' that cane has been treated with steam by the explosive process, and also that it has been saturated by steam in' a boiler, and then crushed between rollers; but my process is distinct and different from these, and I do not claim either of them ;v but, having thus described my invention? The herein-describedA processl of treating wood for preparing paper stock; that is to say, rst subjecting it to the action of steam, in a closed vessel, then rinsing it with water to remove the dissolved gum and acids, and then cooking it in an alkaline solution, all without removingit from the boiler, substantially as herein set forth. l

' GEO. E. MARSHALL.

Witnesses:

R. J'. DAY, Perrin- G. Annes. 

